Ellipsograph with guide



May 6, 1952 w. w. SCOTT ELLIPSOGRAPH WITH GUIDE Filed Oct. 7, 1950 ATTOlQ/VE'YS Patented May 6, 1952 .t

I UNITED STATES PATENT} OFF-ICE? ELLIPSOGRAPH WITH GUIDE Walter w. Scott, Dents, Colo. Application October 7, 1950, Serial No. 18,981 (o1. ss-sn- 3 Claims.

' This invention relates to improvements in ellipsographs with reference more particularly to guides for the-same. i

v This invention relates to an improved guide'or holder for disk ellipsographs of the type shown and described in U. S. Patent 2,468,320 of April 26,1948. V 1

It is the principal object of this invention to produce a guide-or'holder for ellipsographs of the type having two relatively adjustable circular disks of the type shown in the above identified patent. i v

In order thatfan ellipsograph of the type mentioned may begconveniently operated, it is desirable to have the, disks mounted in a guide or frame in which each disk revolves in its own bearing, whichat" the same time is constrained to a rectilinear movement at right angles to the other disk, the extent of the two movements being determined by the size and eccentricity of the disks.

The invention will be most readily understood when reference is had to the accompanying drawing in which the invention is illustrated in its preferred form, and in which:

Figure 1 is a top plan view of the assembly and shows the manner of supporting the disks for rotation and guiding them along rectangular axes; v 1 a Figure} is a section taken on line 2-4, Figure 1; i

. Figure 3 is an end elevation looking through plane 3-3, Figure l;

Figure 4 is a section taken on line 4--4, -Figure 1; Figure 5 is a fragmentary section taken on line 5-5, Figure 1; l v f Figure 6 is a section similar to that shown in Figure 4 showing a slight modification;

Figure 7 is a diagrammatic representation of the two circular. disks showing them adjusted to scribe the ellipse shown by broken lines; and

Figure 8 is a view similar to thatshownin Figure 7 showing the disk assembly turned through 90 degrees.

Referring now to the drawing, reference character X designates the horizontal arm of a rectangular guide whose other arm has been-designated by reference character Y, the point of intersection being designated by reference character 0. These two arms are in the nature of rectangular coordinate axes, and may be positioned in the right angle between the two arms of a drafting machine when the ellipsograph is in use. In the embodiment shown, arms X and Y have considerable width and are provided at the intersection with a rectangular projection Ill and at their ends with upwardly extending flanges H and l I. Metal rods l2 and I3 are positioned between flanges" I i, II and projection ID in the manner shown quite clearly in Figure l.- A plate 14 is provided at its ends with two flanges l5 and [6 that project upwardly and are perforated for the reception of guide rod 12. Plate [4 extends inwardly to a point a short" distance beyond the inner edge of ,arm X and has cemented or otherwise attached thereto a plate H which has a circular inner bearing surface l8 and terminates at point l9 as shown in Figure l. A circular disk A is positionedin the arcuate loop or opening in plate I! and the concave surface of the'latter has a V-groove like that designated by;.:reference numeral 20 in Figure 5. The periphery .of disk A is transversely-V-shaped and fits groovelll so that the two' parts interlock in a" manner to permit relative rotation and prevent disk A from accidentally falling out of its bearing. A plate 2 I, which is somewhat similarto plate I1, is positioned to rest on the upper surface of arm 'rY between it and guide rod I3. Plate H is provided with projections .22 and 23 that are per-, forated for the reception of guide rod l3. -Plate 2| projects outwardly and has an arcuateloop whose extent is greater than 180 degrees in which disk "B? is mounted for rotation. From Figure 5 i will be seen that the concave surface of the 100 or opening in plate 2| has a' Vrgroove with which the correspondingly shaped edgeuof disk B cooperates. It will now be seen thatrdisk A is carried'i by plate I! and mounted for rotation therein, theci'rcular loop or recess in which it is mounted extending more thanl;degrees so as to hold it from accidentally falling I out" .of its bearing. Disk B is similarly mounted, and'ithe two disks with their bearings are movable along right angularly related paths; Disk A is provided with a 'diametrical opening or "slot 24 which, in the embodiment illustrated, has been shown as extending equal distances from opposite sides of the center line of the disk, but which may extend principally from one-side of the center line if desired. Disk '3 is 'prb'vidci with a diametrical slot 25 of substantially-the -same width as slot 24. A screw haying an enlarged flat thin head 21 extends through both slots 24 and 25 in the manner shown in Figure 4 and is provided with a clamping nut 28. By means of this screw the tension disks may be clamped in adjusted position and held against relative rotation by friction. The unthreaded 3 portion 23 of screw 26 may be rectangular and of a size to fit the groove snugly and will thus serve to positively prevent the disks from rotating relative to each other. A scriber having a holder 30 from which a lead 3| projects is attached to screw 26 by means of a cylindrical projection 32 attached to the screw and an arm 33 extending from the scriber and passing through an opening in part 32. A set screw 34 serves to clamp the scriber in adjusted position. In Figure 6 .a slightly modified construction has been shown in which the scriber, instead of being attached to screw 26 by the means shown, is clamped in.

position by means of a nut 35.

Referring now more particularly to Figure '7, line 36 designates the diameter of disk A and line 31 designates the diameter ordisk B, the centers of the two disks being respectively C1 and C2, while the point where the lead is positioned has been designated by P. In setting the scriber with relation to the two disks and with relation to the axes: of; the-ellipse that is desired to be scribed, the distance from the center of disk B to pointP taken equal to one-half the minor axis of the ellipse andv the distance from P to the center line, or disk A. is taken as equal to one-half the major axis of, the ellipse. With the proper relation of, the,v disks and the lead or scriber. point selected and the two disks held against relative rotation or transverse movement, they are. then rotated, over the paper on which the ellipse is to be drawn. It will be seen from the drawing that. disk A rotates with its periphery a fixed distance from. guide rod 12, and ii it, moves longitudinally its, center C1 moves in a straight line. Disk B. similarly rotates with its center a fixed distancefrom guide bar I3 and can move parallel with this bar. Since the two disks are clamped in eccentric relation, it is evident that when the two'disksare. rotated there will be a simultaneous movement of the disk centers parallel to their respective guide axes, and since the scriber or pencil point is positioned eccentrlcally with respecttto the. two disks, it follows that it will scribe an ellipse. similar to. that shown and described in the. patent above identified. Applicant claims no invention in the two disk ellipsograph shown in. Figures '7 and 8, but limits his claims to novelty to the holder shown in Figures 1 to .6, inclusive.

' By rotatably securingthe disks to holders in which they are rotatably .connected and mounting the holders for movement along rectangular axes -arrassembly is produced that can be conveniently operated, eitherby positioning arm. X. against a zT-square and holding it from'longitudina'l movement thereonduring the time the disksfare rotated, or by: positioning. the assembly in the; inside anglezof a drafting machine having right angulazily-related arms.

In the drawing the disks are connected with their respectivebearings or holders by means of Wshaped grooves and projections. This, however, may be replaced by any other suitable means 1: reason is found for substituting other bearings.

The operationof the two disks is clamping, screws and the scriber However. any

4 other suitable material may be employed. It is, of course, possible to construct the entire device from metal such as aluminum, and applicant therefore does not desire to limit himseli to any particular material. It is also possible and practicable to substitute for the guide bars 12 and I3 dove-tailed slots and projections or any other suitable guide means if such a change should be deemed advantageous.

Having described the. invention, what: I claim as new is:

1. In an ellipsograph of the type having two circular disks of different diameters assembled in eccentricv superposed relation and held against relative rotation, there being a scriber point positioned in the diameter of greatest eccentricity and so located that its distance from the center of the larger disk is one-half the major axis and its distance from the center of the smaller disk is equal to one-half thev length of the minor axis; a device for supporting and guiding the disk assembly for rotation and constraining. the two disks to move with their centers in straight right angularly related paths, comprising a member having two right angularly related arms, plates positioned for movement in the plane. of the upper surface of each arm, mean for attaching the plates to their respective arms. for right angular longitudinal rectilinearmovement, each plate having an arcuate. bearing surface of more than 1.80. degrees, one of said plates being-in a plane below the other, the radius of curvature of the bearing surface in the lower plate being the same as the radius of the larger disk and the radius of curvature of the bearing surface in the upper plate being the same as the radius of the smaller disk, the disks being positioned in their respective bearings, whereby when the disksare clamped in eccentric position and rotated as a unit, the bearing plates will constrain them to move with their centers moving simultaneously in right angularly related paths.

2. A guide device in accordance'with claim 1 in which each arm carries a guide rod positioned above the plate and in which the latter has spaced bearings through which the guide rod projects and along which the plate moves, the two'guid'e rods being right angularly related.

3. A guide device in accordance with claim l in which the upper surfaces of the arms 'lie in the same plane andin which the plate having the larger bearing is positioned-underneath the other plate and in which that part. on top of theguide arm is oifset from the part having the bearing the thickness of the plate whereby the upper surface of the-part having thebearing will be in the plane of the upper surface of the corresponding arm.

WALTER W. SCOTT.

REFERENCES CITED The following references are or record in the file of this patent:

UNITED STATES PATENTS Arnemann Apr. 26, 1949 

